A secretive funding organisation in the United States that guarantees anonymity for its billionaire donors has emerged as a major operator in the climate "counter movement" to undermine the science of global warming, The Independent has learnt.

The Donors Trust, along with its sister group Donors Capital Fund, based in Alexandria, Virginia, is funnelling millions of dollars into the effort to cast doubt on climate change without revealing the identities of its wealthy backers or that they have links to the fossil fuel industry.

However, an audit trail reveals that Donors is being indirectly supported by the American billionaire Charles Koch who, with his brother David, jointly owns a majority stake in Koch Industries, a large oil, gas and chemicals conglomerate based in Kansas.

Millions of dollars has been paid to Donors through a third-party organisation, called the Knowledge and Progress Fund, with is operated by the Koch family but does not advertise its Koch connections.